I have microsoft office 2003 on this computer

and I have office 2007 on a computer in FL. I don’t like the o7 as well so I’ve kept the 03 up here even though I have 2 downloads left for the 07. Maybe it’s just a matter of getting used to the 07 but I’d prefer not to install it here. I received a document created in 07 and I’m asked if I want to download a compatability pack so I can open it. Is that just for read only? Another question: if I do download the o7 on this computer, what happens to all of my saved 03 documents?
Thanks.